It is conventional to employ measuring stops on mat cutting machines for quickly and easily locating the starting and ending points of cuts to be made. As described in Kozyrski et al U.S. Pat. No. 4,871,156, issued Oct. 3, 1989, such measuring stops are slidably mounted upon the shaft or rail of the mat clamping bar of the machine, and means is provided on the stop itself for locking it at any selected point along the length of the shaft. Although the measuring stops described by Kozyrski et al are entirely satisfactory for their intended purpose, it has now been recognized that certain of their features could be improved upon.
More particularly, installation of the measuring stops of the aforementioned patent requires some disassembly of the clamping bar, which is of course inconvenient and time consuming. Also, the main elements of the locking mechanism for those stops are integral parts of the stop body, and the constant establishment and maintenance of strong clamping forces tends to overstress and distort the material from which the body is fabricated; such distortion may inhibit full release and free sliding on the shaft, and can ultimately render the clamp completely ineffectual. Indeed, even in the absence of such overstressing the locking mechanism of the Kozyrski et al patent may not produce a sufficient clamping force to withstand the impact to which the stops are repeatedly subjected during normal operation of the machine.
Accordingly, it is the broad object of the present invention to provide a measuring stop assembly that is quickly and conventiently mounted upon the clamping bar shaft, and which affords an improved locking action while, at the same time, avoiding overstressing of the material from which the stop is constructed.
It is a related object of the invention to provide a mat cutting machine in which is employed a measuring stop having the foregoing features and advantages.
More specific objects of the invention are to provide such a measuring stop and machine in which there is no need for removal of the shaft, or other parts of the clamping bar assembly, to enable installation of the stop thereupon, and in which a favorable mechanical advantage affords a highly effective and yet simple locking mechanism.